Clip-on sunglasses comprises a spectacle frame with clipping claws adapted for firmly mounting on a shortsighted or farsighted eyeglasses, so that the wearer does not need to have another pair of shortsighted or farsighted sunglasses. However, the wearer must take down his and her primary eyeglasses and requires both hand operations in order to correctly mount the clip-on sunglasses on the primary eyeglasses. Such mounting operation is impossible when the wearer is driving. Moreover, the metal made clipping claws will scratch on the lenses of the primary eyeglasses during the mounting operation.
In order to solve the problems of the above mentioned clip-on sunglasses, magnetic attachment is recently introduced into the eyeglasses industry. For, example, U.S. Pat. No. 5,568,207 suggests spectacle frames comprising a primary spectacle frame having a primary pair of magnet members provided on the two upper side extensions respectively, and an auxiliary spectacle frame such as a sunglasses including a pair of arms for engaging over the two upper side extensions for preventing the auxiliary spectacle frame from moving downward relative to the primary spectacle frame and having an auxiliary pair of magnet members for engaging with the primary magnet members of the primary spectacle frame and for stably attaching the auxiliary spectacle frame to the primary spectacle frame. However, the users have to align two pair of magnet members. If the auxiliary magnet members of the sunglasses are misaligned with the primary magnet members of the primary spectacle frame, the sunglasses will fall down from the primary spectacle frame accidentally and easily.
Other U.S. patents such as U.S. Pat. Nos. 5,416,537, 5,642,177, and 5,737,054 all provide an attachable sunglasses adapted to be attached on a primary eyeglasses through magnetic members.
In U.S. Pat. No. 5,416,537, a pair of magnet members are engaged on two top corners of the primary frame so that a sunglasses frame having another pair of magnet members affixed on respective top corners thereof can be attached in front of the primary frame. However, the front magnet members on the primary frame may destroy the entire ornamental appearance of the primary frame.
In U.S. Pat. No. 5,642,177, although the front magnet members are moved to two side extensions. It still bears similar drawbacks of adversely affecting the appearance of the eyeglasses.
In U.S. Pat. No. 5,737,054, it tries to save the cost of two magnet members. However, the alignment of the front auxiliary lenses becomes more difficult and the attachment of the front auxiliary lenses becomes unstable too. A slightly head shake may cause the auxiliary lenses off position or even falling down.
Furthermore, all conventional magnetic attachable sunglasses as mentioned above have a serious common shortcoming that makes the magnetic attachable sunglasses still can not work better than a clip-on sunglasses, i.e. the magnetic attachable sunglasses may easily drop off when the wearer does exercise or is fast moving. It may fall down during jumping, running or head shaking. In other words, such magnetic attachable sunglasses are unsuitable to be used during sporting activities. However, all users especially need sunglasses during outdoor sports or exercising. Moreover, the conventional magnetic attachable sunglasses will fall down when the two temples are stretched apart. Therefore, such magnetic attachable sunglasses do not fit to most sporters or some people who have wide faces.
Besides, the weight of the eyeglasses is heavier than usual because of the additional magnet members installed thereon for ensuring magnetic attraction with the sunglasses. Also, the magnet members on the primary frame, according to the prior arts, adversely affect the entire ornamental appearance of the primary frame.